The skins of an elevator, in Long Range (LR) & Single Aisle (SA) type aircraft, are manufactured with sandwich type composite materials.
Sandwich type composite material skins are manufactured by attaching two thin, but stiff skins (typically made from carbon fibre reinforced plastic laminates) to a lightweight but thick core (usually open and closed-cell structured foams). The core must have a minimum thickness in order to withstand the pressure transferred by the carbon fibre reinforced laminates during the curing cycle wherein a high temperature and pressure is applied; otherwise the core would collapse under said pressure.
Trailing edges of aircraft structures are formed by joining the upper skin and the lower skin of said aircraft structure. The thickness of the upper skin and of the lower skin decreases in the area of the trailing edge, in order to achieve the desired aerodynamic profile.
When the upper skin and the lower skin of said aircraft structure are made of sandwich type composite materials, due to the minimum core thickness requirement for each skin, there is a change in the slope of the upper skin and the lower skin, which worsens the aerodynamic profile of the aforementioned trailing edge.
In order to achieve a continuous aerodynamic profile, the upper and lower skins are currently joined by a clip type metal sheet, with a U-shape and the remaining space is filled with a paste until the desired continuous aerodynamic profile is obtained. This paste, when used in a huge quantity, becomes chapped and falls off the stabilizers, carrying, with the falling off of the paste, the paint of the aircraft. This falling off increases the profile drag and the falling off is an esthetic drawback that is the cause of many complaints from airlines.
Document WO 2010/070185 A2 discloses a trailing edge structure according to the prior art, in which the upper and lower skins are joined by a clip-type element with recesses where the inner surfaces of both the upper skin and the lower skin are coupled to said element, placing a paste on the clip-type element until the aerodynamic desired profile is obtained.